Animals first appeared in the fossil record in the late Cryogenian period and diversified in the subsequent Ediacaran period in what is known as the Avalon explosion. Nearly all modern animal phyla first appeared in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. Common to all living animals, 6,331 groups of genes have been identified that may have arisen from a single common ancestor that lived about 650 Mya during the Cryogenian period. (Full article...)
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A juvenile Aliger gigas displaying the spiral-shaped shell with a glossy pink and orange interior, part of the soft interior body, and large eyes on the end of stalks.
The queen conch is herbivorous. It feeds by browsing for plant and algal material growing in the seagrass beds, and scavenging for decaying plant matter. These large sea snails typically reside in seagrass beds, which are sandy plains covered in swaying sea grass and associated with coral reefs, although the exact habitat of this species varies according to developmental age. The adult animal has a very large, solid and heavy shell, with knob-like spines on the shoulder, a flared, thick outer lip, and a characteristic pink or orange aperture (opening). The outside of the queen conch is sandy colored, helping them blend in with their surroundings. The flared lip is absent in juveniles; it develops once the snail reaches reproductive age. The thicker the shell's flared lip is, the older the conch is. The external anatomy of the soft parts of A. gigas is similar to that of other snails in the family Strombidae; it has a long snout, two eyestalks with well-developed eyes, additional sensory tentacles, a strong foot and a corneous, sickle-shaped operculum. (Full article...)
The leopard shark (Triakis semifasciata) is a species of hound shark found along the Pacific coast of North America from the U.S. state of Oregon to Mazatlán in Mexico. Typically measuring 1.2–1.5 m (3.9–4.9 ft) long, this slender-bodied shark is characterized by black saddle-like markings and large spots over its back.
The common clam worm (Alitta succinea) is a widely distributed species of marine polychaete worm. The photograph shows an epitoke specimen, the worm having turned into a form capable of reproduction. After releasing its sperm or eggs, the animal will die.
Platyhelminthes (from Ancient Greekπλατύ (platy)'flat' and ἕλμινς (helmins)'parasitic worm') is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratoryorgans, they are restricted to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food can not be processed continuously. (Full article...)
The brown pelican (Pelecanus occidentalis) is a bird of the pelican family, Pelecanidae, one of three species found in the Americas and one of two that feed by diving into water. This photograph shows a juvenile brown pelican gliding over the Pacific Ocean at Bodega Head, California.
After hatching, the pelican chicks are fed on regurgitated predigested fish and take about two months to fledge. When they leave the nest, they are at first unable to fly and take wing several weeks later. When the parents cease to feed them, some six months later, each will have consumed around 70 kg (150 lb) of fish. The juvenile brown pelican does not acquire adult plumage until three years of age, when the feathers on the neck become paler, the upperparts striped, the wing feathers grayer, and the belly acquires dark spots.
The rock hyrax (Procavia capensis), also known as the dassie, is one of four living species of the order Hyracoidea, and the only living species in its genus. Like all hyraxes, it is a medium-sized terrestrial mammal between 4 kilograms (9 lb) and 5 kilograms (11 lb) in mass, with short ears and tail. The rock hyrax is found across Africa and the Middle East, at elevations up to 4,200 metres (13,800 ft). It resides in habitats with rock crevices which it uses to escape from predators. Along with the other hyrax species and the manatee, these are the animals most closely related to the elephant.
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquaticinvertebrate animals, nearly all living in sedentary colonies. Typically about 0.5 millimetres (1⁄64 in) long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. The bryozoans are classified as the marine bryozoans (Stenolaemata), freshwater bryozoans (Phylactolaemata), and mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. 5,869living species of bryozoa are known. Originally all of the crown group Bryozoa were colonial, but as an adaptation to a mesopsammal (interstitial spaces in marine sand) life or to deep-sea habitats, secondarily solitary forms have since evolved. Solitary species have been described in four genera: Aethozooides, Aethozoon, Franzenella, and Monobryozoon, the latter having a statocyst-like organ with a supposed excretory function. (Full article...)
Liguus virgineus, also known as the candy cane snail, is a species of snail in the family Orthalicidae. It is native to the Caribbean island of Hispaniola, in the nations of Haiti and the Dominican Republic. There have also been at least three reports of living specimens being found in the Florida Keys of the United States. The snail lives on trees and feeds on moss, fungi and microscopic algae covering the bark.
The paddyfield pipit (Anthus rufulus) is a passerine bird in the family Motacillidae, comprising pipits, longclaws and wagtails. About 15 cm (6 in) in length and native to southern Asia, its plumage in both sexes is greyish-brown above and paler yellowish-brown below, with dark streaking on the breast. A bird of open country, pasture and cultivated fields, it sometimes makes short flights, but mostly runs on the ground, foraging for insects and other small invertebrates. The paddyfield pipit builds its cup-shaped nest in a concealed location on the ground, and may have two or more broods in a year. This A. r. rufulus individual was photographed in Kanha Tiger Reserve, in the Indian state of Madhya Pradesh.
Eutropis macularia, the bronze grass skink, is a species of lizard in the skink family, Scincidae, native to South and Southeast Asia. It lives in both deciduous and evergreen forests, in plantations, in grasslands, and in rocky areas with scattered trees. The species is active in both the day and the night, feeding on insects and other invertebrates. This bronze grass skink was photographed on a tree trunk on the island of Don Det in Laos.
A cross section of a post-clitellum segment of an annelid (ringed worm); almost all segments of an annelid contain the same set of organs and parts, a pattern called metamerism. Annelids have no lungs, but rather exchange carbon dioxide and oxygen directly through the moist skin when blood reaches the extremely fine capillaries of the body walls; a dry worm cannot breathe and will die of suffocation. The worm's red blood, which does not consist of platelets or red cells but mostly of a liquid containing suspended hemoglobin, makes a circuit up and down the animal in its closed circulatory systems.
Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus'brittle star'; from Ancient Greekὄφις (óphis)'serpent' and οὐρά (ourá)'tail'; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to 60 cm (24 in) in length on the largest specimens. (Full article...)
The Atlantic spadefish is a species of marine fish endemic to the shallow waters off the coast of the southeastern United States and in the Caribbean Sea. They are similar in appearance to fresh waterangelfish, but much larger, reaching up to three feet (0.9 m) in length. Due to their reputation as strong fighters, they are popular game fish, especially during the summer months when they are most active.
A soybean cyst nematode (Heterodera glycines), together with an egg, as viewed through a low-temperature scanning electron microscope at 1000x magnification. This nematode infects the roots of soybeans, and the female nematode eventually becomes a cyst. Infection causes various symptoms that may include chlorosis of the leaves and stems, root necrosis, loss in seed yield and suppression of root and shoot growth.
A female Calliope Hummingbird (Stellula calliope), the smallest bird found in Canada and the United States, feeding insects to chicks. Found mostly in western North America (although vagrants have been found in New York and Connecticut), it is migratory and winters in southwestern Mexico.
...that six new species of marine slugs in the genus Phyllodesmium(Sp. kabiranum pictured) have been described in the last two years?
...that Maui's dolphin is the most endangered species of dolphin in the world, with only about 110 left?
...that the land snail Euglandina rosea is a significant threat to Hawaiian freshwater snail known as Newcomb's snail (Erinna newcombi), because the predatory Euglandina is able to hunt Erinna under water?
...that the body of the "X-ray fish" (Pristella maxillaris ) is so transparent that it is possible to see its backbone?
The following are images from various animal-related articles on Wikipedia.
Image 1A praying mantis in deimatic or threat pose displays conspicuous patches of colour to startle potential predators. This is not warning coloration as the insect is palatable. (from Animal coloration)
Image 6A gun dog retrieving a duck during a hunt (from Animal)
Image 7The microscopic cave snail Zospeum tholussum, found at depths of 743 to 1,392 m (2,438 to 4,567 ft) in the Lukina Jama–Trojama cave system of Croatia, is completely blind with a translucent shell (from Fauna)
Image 8The black and yellow warning colours of the cinnabar moth caterpillar, Tyria jacobaeae, are avoided by some birds. (from Animal coloration)
Image 9A brilliantly-coloured oriental sweetlips fish (Plectorhinchus vittatus) waits while two boldly-patterned cleaner wrasse (Labroides dimidiatus) pick parasites from its skin. The spotted tail and fin pattern of the sweetlips signals sexual maturity; the behaviour and pattern of the cleaner fish signal their availability for cleaning service, rather than as prey. (from Animal coloration)
Image 10Simplified schematic of an island's fauna – all its animal species, highlighted in boxes (from Fauna)
Image 11The red pigment in a flamingo's plumage comes from its diet of shrimps, which get it from microscopic algae. (from Animal coloration)
Image 12Squid chromatophores appear as black, brown, reddish and pink areas in this micrograph. (from Animal coloration)
Image 26Non-bilaterian animals include sponges (centre) and corals (background). (from Animal)
Image 27The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus. (from Animal)
Image 44Idealised nephrozoan body plan. With an elongated body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the basis of the head. Opposed circular and longitudinal muscles enable peristaltic motion. (from Animal)
The following table lists estimated numbers of described extant species for the animal groups with the largest numbers of species,[1] along with their principal habitats (terrestrial, fresh water,[2] and marine),[3] and free-living or parasitic ways of life.[4] Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million.[5] Using patterns within the taxonomic hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011.[6][7][a]
^The application of DNA barcoding to taxonomy further complicates this; a 2016 barcoding analysis estimated a total count of nearly 100,000 insect species for Canada alone, and extrapolated that the global insect fauna must be in excess of 10 million species, of which nearly 2 million are in a single fly family known as gall midges (Cecidomyiidae).[8]
^Stork, Nigel E. (January 2018). "How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth?". Annual Review of Entomology. 63 (1): 31–45. doi:10.1146/annurev-ento-020117-043348. PMID28938083. S2CID23755007. Stork notes that 1m insects have been named, making much larger predicted estimates.
^ abcdNicol, David (June 1969). "The Number of Living Species of Molluscs". Systematic Zoology. 18 (2): 251–254. doi:10.2307/2412618. JSTOR2412618.
^Sluys, R. (1999). "Global diversity of land planarians (Platyhelminthes, Tricladida, Terricola): a new indicator-taxon in biodiversity and conservation studies". Biodiversity and Conservation. 8 (12): 1663–1681. doi:10.1023/A:1008994925673. S2CID38784755.
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